The Computer Numerical Controlled (CNC) mill a mill which is controlled by a computer. Anything which could be made using a mill can be made more precisely and quickly with a CNC mill.

A mill is a subtractive manufacturing processes where the raw material is affixed to the table and a drill is placed into a spindle which rotates the drill. The table moves around in relation to the drill in order to make cuts which removes material from the raw form. Often times the drill has a vertical motion which simulates raising or lowering the table.

A CNC mill is controlled by a computer rather than manually controlled. A machinist writes a program using a variant of G-code which is a step by step process describing how to make a part given a piece of raw material of known dimensions. Alternatively, Computer Aided Manufacturing (CAM) converts a CAD drawing into G-code. This eliminates bugs which arises from converting CAD to G-code by hand as well as allows for more complex curves which would take more time to code. After the program is coded and fully debugged, the raw material is fixed onto the table and the origin of the material is found and zeroed on the machine. When the program is run, the computer follows the program line by line and feeds the instructions to the mill. When the program is completed, the finished part is taken out.